The present invention relates to controlling sulfur and arsine emissions. The present invention more particularly relates to the control of hydrogen sulfide and arsine emissions during the processing of ore, such as tantalum-bearing ore.
The control of some emissions, such as hydrogen sulfide or arsine, are important since such emissions are either identified as pollutants or at a minimum create undesirable odors. In the processing of ore, such as tantalum-bearing ore, ore can contain various amounts of sulfur which can be released upon the processing of the ore. For instance, when various materials are recovered from ore such as metals, the ore is typically crushed and then subjected to a digestion. In the digestion, the ore is subjected to various treatments such as an acid treatment, which is used to dissolve various parts of the ore in order to aid in the recovery of the targeted materials. In the case of tantalum-bearing ore, tantalum is typically recovered from tantalum-bearing ore by subjecting the crushed ore to a digestion wherein acids, such as hydrofluoric acid, are mixed into the crushed ore in order to dissolve the ore to form a digestion liquor and typically an ore residue. The tantalum which is present as a tantalum compound is then dissolved by such a acid treatment and recovered by solvent extraction and other techniques, for instance as described in U.S. Pat. Nos. 6,338,832, 6,348,113 and in Miller, xe2x80x9cTantalum and Niobiumxe2x80x9d (Academic Press, Inc., Publishers, 1959), for instance but not limited to, pages 1-100, all patents and publications incorporated in their entirety by reference herein. During this digestion the sulfur and possible arsine are released.
While there may be various techniques to remove the sulfur prior to being subjected to a digestion process, such efforts are costly and typically may not remove all of the sulfur necessary to reduce sulfur odor. Furthermore, activated carbon could be used, however the activated carbon would create a cumbersome process and the activated carbon may be temperature sensitive. Furthermore, the activated carbon most likely would increase the amount of ore residue. Furthermore, past experience has shown that activated carbon may not be a consistent system with its results on a day to day operation.
Also, a caustic scrub could be used to eliminate the sulfur odor. However, the cost of using such a caustic scrub is very expensive and the maintenance of maintaining a scrubber can be costly as well.
Also, a carbon bed could be used to reduce sulfur odor. However, these carbon beds are also quite expensive and there is a large operating cost to maintain the equipment. Also, especially with processing of tantalum-bearing ore, carbon beds may not be the most efficient equipment to use due to high temperatures and oxygen running through the beds.
Accordingly, there is a need to provide an effective means to control hydrogen sulfide and/or arsine emissions in a cost efficient manner.
All the patents and publications mentioned above and throughout are incorporated in their entirety by reference herein.
A feature of the present invention is to provide methods to control hydrogen sulfide and/or arsine emissions, especially during the processing of ore.
Another feature of the present invention is to provide a method to control hydrogen sulfide and/or arsine emissions which do not require expensive equipment or materials.
A further feature of the present invention is to provide a method to control hydrogen sulfide and/or arsine emissions which are safe, efficient, and do not increase ore residue nor effect the quality of the material being recovered from, for instance, the ore.
Additional features and advantages of the present invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.
To achieve these and other advantages, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates to a method to control hydrogen sulfide and/or arsine emissions by adding at least one copper compound to the material which causes the hydrogen sulfide or arsine emissions.
The present invention further relates to a method to control hydrogen sulfide and/or arsine emissions during the processing of ore. The method includes adding at least one copper compound to the ore in an amount sufficient to control the emissions.
The present invention further relates to methods to control hydrogen sulfide and/or arsine emissions during the digestion of ore, such as tantalum-bearing ore. The method involves adding at least one copper compound to the tantalum-bearing ore during the digestion.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present invention, as claimed.